Re: Severe netbsd-6 NFS server-side performance issues

[buhrow%lothlorien.nfbcal.org@localhost (Brian Buhrow)]

        hello.  Hmm.  A panic a week?  I wouldn't call that stable at all.
However, one issue at a time.
        Does the raid controller have some sort of battery backed up cache?
Which driver supports these raid controllers?  mfi(4)?
        I'm not sure of the problem, but it sounds like some sort of write
back cacheing switch got flipped in the raid controller, and now writes,
with interleaving reads, are really slow.  I'm assuming you've looked at
the BIOS of the raid controller to see if there are any settings which
might have to do with caching?
        Is it possible to revert to the NetBSD-5.x system and see if your
performance goes back  to where it was  after the raid upgrade but before
the OS upgrade?
        If you export a non-raid disk, what kind of nfs performance do you get
on the system when writing to that disk?  (That will help you figure out if
it's a raid problem or an OS problem.)
        I realize that I'm more questions than answers, but I think the
question you're trying to answer is, what changed?  The answer is, I think,
something about the raid system.

-Brian

On May 30,  9:06pm, Hauke Fath wrote:
} Subject: Re: Severe netbsd-6 NFS server-side performance issues
} At 10:03 Uhr -0700 30.5.2012, Brian Buhrow wrote:
} >Was this machine running ans serving nfs under NetBSD-5?
} 
} Yes.
} 
} > How
} >was its performance there?  Did the performance go to heck when you did the
} >raid upgrade?
} 
} The machine ran stably (uptime 150 d) under netbsd-5 with a MegaRAID 320-2
} controller. After the upgrade with the 320-4X, performance was good (i.e.
} better than before the upgrade), but the machine began to be flaky: After a
} day or three, the nfsd would just stop serving, making a reboot necessary.
} 
} Upgrading to netbsd-6 partly fixed that, but brought up other issues; I
} guess the increased data throughput hit a few kernel limits. After
} kern/46136 had been fixed, the machine ran mostly fine (as in: a panic a
} week) and performed well (> 100 MBytes/sec peak) for about two weeks, after
} which performance broke in as described.
} 
}       hauke
} 
} 
} 
} --
} "It's never straight up and down"     (DEVO)
} 
} 
>-- End of excerpt from Hauke Fath